<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<iframe id="i" src="/common/blank.html"></iframe>
<script>
async_test(t => {
  let start_length = navigation.entries().length;
  let start_index = navigation.currentEntry.index;
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  window.onload = () => t.step_timeout(() => {
    assert_equals(navigation.entries().length, start_length);
    assert_equals(i.contentWindow.navigation.entries().length, 1);
    navigation.navigate("#top");
    assert_equals(navigation.entries().length, start_length+1);
    assert_equals(i.contentWindow.navigation.entries().length, 1);
    i.contentWindow.navigation.navigate("#1");
    assert_equals(navigation.entries().length, start_length+1);
    assert_equals(i.contentWindow.navigation.entries().length, 2);
    assert_equals(navigation.currentEntry.index, start_index+1);
    assert_equals(i.contentWindow.navigation.currentEntry.index, 1);
    assert_true(navigation.canGoBack);
    assert_true(i.contentWindow.navigation.canGoBack);

    i.contentWindow.navigation.back().committed.then(t.step_func(() => {
      assert_equals(navigation.currentEntry.index, start_index+1);
      assert_equals(i.contentWindow.navigation.currentEntry.index, 0);
      navigation.back().committed.then(t.step_func(() => {
        assert_equals(navigation.currentEntry.index, start_index);
        assert_equals(i.contentWindow.navigation.currentEntry.index, 0);
        // There are 2 joint session history entries containing the top window's
        // final key. Navigate to the nearest one (which navigates only the
        // top window).
        navigation.forward().committed.then(t.step_func_done(() => {
          assert_equals(navigation.currentEntry.index, start_index+1);
          assert_equals(i.contentWindow.navigation.currentEntry.index, 0);
        }));
      }));
    }));
  }, 0);
}, "navigation.forward() goes to the nearest forward entry");
</script>
